Apparatus for recovering sulfur dioxid from gases



A. H. EUSTIS.

APPARATUS FOR RECOVERING SULFUR DIOXID FROM GASES. I

APPLICATION FILED JULYI6,1919.

1,341,115. 11116111111v May 25,1920.

flu (IS/US 172 05725.

AUGUSTUS H. EUSTIS, OF MILTON, MASSACHUSETTS.

APPARATUS FOR RECOUERING SULFUR DIOXID FROM GASES.

Specification of Letters Patent.

Patented May 25, 1920.

Original application filed April 14, 1919, Serial No. 289,857. Dividedand this application filed July 16,

' 1919. Serial No. 311,123.

To all whom it may concern 7 Be it known that I, AUcUs'rUs H. Eusrrs, acitizen of the United States of America, and resident of Milton, in thecounty of Norfolk and State of Massachusetts, ave invented new anduseful Im rovements in Apparatus for Recovering ulfur DlOXld from Gases,of which the following is a May 14, 1918, entitled Method and apparatusfor segregating and recovering gases.

This a lication is a division of apphcation Serial 0. 289,857 filed bymeApril 14, 1919, for a method and apmratus for recovering sulfur dioxidfrom gases with which it may be associated. The present invention has todo princlpally with improvements in those parts of the apparatus bywhich the sulfur dioxid is extracted from the liquor in which it hasbeen absorbed, and by which the extracted.

sulfur dioxid is reduced to liquid or condensed form suitable forcommercial use.

The principal objects of the invention are to safeguard and protect thepump or pumps, by which theextracted SO gas is handled, from thedestructive effects of cor rosion by the gases; to utilize a part of theS0 gas (in liquid form) made by the process to remove substantially thelast traces of water or moisture from the rest of the S0 gases; to makeit possible to eliminate sulfuric acid desiccators heretofore used fordrying the extracted gases, and to combine in the vacuum chamber thefunctions of a gas extractorand a condenser for the steain engine of apower plant, thus utilizing the heat of the exhaust steam foraccomplishing the extraction, eliminating the heat exchanger or makingit possible to use only a small heat exchanger, and saving the heat ofthe exhaust steam which would otherwise be wasted.

In the accompanying drawings which illustrate in diagrammatic formapparatus embodyin the invention, Figure 1 is a diagram of t e'apparatusas a whole, and Figs.

clean and enrich the gases. From tower 2 the gases pass through pipe orflue 3 into scrubbing towers 4, 4:, 4, 4:, in parallel; thence by pipeor fine 5 into scrubbing towers 6*, 6",6, 6, in parallel; thence by pipeor fine 7 into the lime tower 8; and thence by pipe or flue 9 to a stackonthe atmosphere. The hot tower 2, the scrubbing towers 4*, etc.,(which'may be termed the Jr-group) the scrubbing towers 6, etc.,- (whichmay be termed the fi-group), and the tower 8 may all be substantiallsimilar, and are packed with masses 0 broken, solid material insuch-form that water or liquid descending through the towers will bebroken up to present extended superficial areas for contact with theases from the furnace. towers are packed maybe coke, slag or otherinsoluble material, or limestone or other soluble material which willincrease the capacity of the liquid for absorbing S0,, or the packmg maybe in part such insoluble material, and in part such soluble material.Preferably the hot tower 2, and the scrubblng towers of the l-group andthe 6-group, will be lpacked with coke or other insoluble materia whilethe tower 8 will be packed with limestone, or some similar soluble material, to increase the capacity of the liquid to absorb S0,, and thusremove as nearly as possible the last trade-fit SO from the gases.

Water is fed to the 'scrubbing towers of the (S-group audio tower 8 fromany suitable source of silipply through pipe 10, whence it is deliveredin parallel to headers or distributers atthe tops of the several towers,and from the distributers flows or trickles down through the packing.The water from tower 8 flows to waste, or if it is desired to utilizeall the S0,, it may be conducted to either the scrubbers of the 6- grouporthe Jr-group. The water from the towers of the 6-group is collected inpipe 11, and may be disposed of in three ways. Part of it may bedelivered through valve 11* The material with which the into the top ofthe hot tower 2, where it will gases and give up its sulfur dioxid gasthereby enrichin the furnace gases which pass to.- the scrub ers of theL-group; part of the water will be carried by pipe 11 and delivered intothe tops of the scrubbers of the lt-group, through the several towers ofwhich it passes in parallel; and part will probably always be wasted tothe sewer through valve 11*.

7 It will be observed that both the liquids and the gases pass throughthe individual towers of each group in parallel, and through the groupsin series. The water first passing through the scrubbers of the 6-grouptakes up sulfur dioxid gas which still remains in the furnace gasesafter their passage through the scrubbers of the 4:-

group, and is then further enriched as it passes through the scrubbersof the 4- group. The solution from the l-group is collected in pipe 12,and part of it may be delivered through valve 12 into the hot towers 2,where the solution will become heated and give up its gas, therebyfurther enriching the gas which flows to the scrubbers of the 4-group.Whether the solutions from the Jr-group or the 6-group, or either ofthem, are delivered into the hot tower,

will be determined by the operative conditions of the particular plantand the analyses of the solutions as they may be found; and suchdelivery may be controlled by, the valves 11 and 12. The conditions willvary with different supplies of gas, and probably from hour to hour withthe same supply of gas. The remainder of the solution from the scrubbersof the 4-group'will be delivered into a storage tank 13, or wastedthrough valve 12 if the supply exceeds the capacity of the subsequentparts of the apparatus to take care of it.

As thus far described the process and apparatus are the same as setforth in said former Patent No. 1,265,892.

From storage tank 13, which is covered to prevent the escape of SO gas,the solutions flow, aided by the pump 14 if necessary, through pipe 15to the top of a tank or chamber 16, the upper part of which constitutesa douche tank to cool the gases and the lower part of which constitutesa vacuum extractor. The tank 16 is provided with a series of shelves orpans 17 having a central opening 17 a for the passage of gas, andshelves or pans 18 of less diameter than the tank 16 to leave an annularopening 18 around the periphery for the passage of gas. The shelves 17and 18 are arranged alternately as shown, and each shelf overlaps theopening of the next shelf, thus providing a tortuous or sinuous passagefor the gases rising through the tank. The shelves are also perforatedwith a large number of small holes through which the solutions flowbroken up into drops or small streams to expose superficially extensivesurfaces.

The descending solutions thus broken up and spread out are subjected inthe lower part of the tank 16 to the combined effect of heat and vacuumby which the S0 gas is extracted from the liquor. The heat which,combined with the vacuum, accomplishes the extraction of the gas in theextractor (the lower part of tank 16) is supplied through the exhauststeam pipe 22 leading from the steam engine, or turbine 23, whichoperates the plant, or does other work, into the bottom of the extractorchamber. The vacuum is produced by the vacuum pump or pumps, hereinafterdescribed, connected to pipe or flue 20 which leads out of the top oftank 16.

The steam entering the extractor chamher at the bottom of tank 16 heatsthe solution therein, thus eifecting the extraction of the gas inconjunction with the vacuum, and in so doing is condensed; or ifcondensation in the lower part of tank 16 is not complete the exhauststeam rising through the cooling chamber in the upper part of tank 16 istherein wholly condensed.

The S0 gases extracted in the extraction chamber at the bottom of tank16 go upward through the douche tank cooling able of the water vapor,but the solution itself is also somewhat warmed, thereby contributing tothe extraction of the gases in the extractor chamber at the lower partof the tank 16.

It will be observed that the chamber 16 serves as a combined extractorfor the gas and condenser for the exhaust steam, thereby utilizing theheat of the exhaust steam, now usually wasted, for assisting in recovering the gas from the liquor, and doing away with or materiallyreducing the size of the heat exchanger or other specially contrivedsource of heat for accomplishing the extraction such as that shown insaid former patent.

After the gases have been extracted from the solution the liquor flowsout of the bottom of the extractor through pipe 1.) to waste, or to asmall heat exchanger of the character shown in said Patent No.1,265,892, if any is used.

1i. small amount of the gas is. probably reabsorbed in the liquor as itrises throng the upper part of tank 16, but as it is at all timessubject to a vacuum, and as the time during which it is in contact withthe liquor in the cooling chamber of tank 16 is short, the amount soreabsorbed 15 small, and. what little is so reabsorbed again passes intothe extractor chamber and is therefore recovered without loss.

From the top of the cooler or douche tank the gases go by pipe 20 torefrigerators or surface coolers 21 Where they are further cooled bybrine or other suitable agencies, or are refrigerated by an ammoniasystem or the like, and a still further part of the contained watervapor is given up. Any suitable means for cooling and thus drying thegas may be used at this stage. I

From the coolers 21 the gases flow by pipe 25 to vacuum pump 24? whichmaintains the vacuum in the extractor chamber and cooling chamber oftank 16, and in refrigerators 21. With the present invention 1t'1spossible to dispense with all sulfuric acid deslccators shown in saidformer patent, and to use coolers, and liquid sulfur dioxid ashereinafter described, as the desiccating means.

The gases passing through the vacuum pump 24: still contain some watervapor or moisture in condensed or condensing state. Vet acid gases,thatis, gases carrying liquid acids or free water or water va )or,attack and rapidly corrode the pump. find, however, that if the gaseswhich come in contact with the pump are dry, that is, are free of liquidacids, water or other liquid, they are practically harmless. conceivablythe gases could be rendered substantially, dry and harmless by raisingthe temperature of the entire body of the gas above the dew point beforeit enters the pump, but this is costly and unnecessary provided the gasactually contacting with the walls and surfaces of the pump and itspartsis raised above the dew point and thus rendered dry andnondestructive. To accomplish this I provide the ump as with a steamjacket 27 supplied with hot steam through pipe 28 from any suitablesource adapted to raise the tem' perature of the pump 24 to such pointthat the heat of the pump will raise the temperature of the gases inactual contact therewith above the dew point, thus depriving the gases.in contact with the pump of free water, condensed or condensing vaporor other moisture. It is not necessary that the part of the gasespassing through the pump but not actually bathing or contacting with itssurface should be so dried, nor that heat should be expended to thatend. The heat supplied to the steam jacket 27 can be regulated andcontrolled by a valve 29 or in any convenient manner.

When the apparatus is first started up the temperature of the pump israised to the desired point by adn'iitting steam to the steam jacket.After operation for a while a part of the heat and in some instances thewhole of the heat required will be supplied by the heat of con'lpressionoi the pump itself. Indeed, it may develop with some apparzuuis that thepump will. become too hot from the heat of compression, and inthat eventthe steam in the jacket 27 may be replaced by water circulation toreduce the heat. Iii short, the purpose of the jacket 27 is to coir trolthe heat of the pump, whether by raising or lowering the tem iieraturc,the essential condition being that the temperatiu'e of the pump bemaintained. at such point that the gases in immediate eonta with itssurfaces, that is, at least a lihn or layer of the gases actuallycontacting with the. sur faces of the pump, be raised by the heat of thepump above the dew point with. respect to the liquids contained in thegases,

From vacuum pump 24 the. gases, compressed by the pump, are deliveredinto a cooler 26,-whichma'y be a surface cooler similar to 21, andtherein cooled. The cooling of the gases in 26 condenses out part of theremaining water or other liquid. Thence the gases are drawn by pump 24*,further compressed thereby, and delivered to another cooler 26", similarto 26, and therein further cooled and dried. The pump 24: may be kept atthe desired temperature by a jacket 27*, supplied with steam or othertemperature controlling fluid through valve 29" in the inlet pipe, inthe same manner an d for the same purpose as already described inconnection with pump 24. From cooler 26" the gases are d awn by pump24,similarly inclosed in a jacket 27 controlled. by valve '29, furthercompressed thereby, and delivered into anotier cooler 26 similar tocoolers 26 and 26f, and therein iurther cooled and dried. From cooler 26the gases pass to cooling chamber 30, which still further cools thegases and condenses out most of the remaining water or other liquid, andthe latter is removed tl'irough pipe 53 In order that the coolers 2626", 2'26 and .30 may not be vulnerable to attack by the ture above thedew point of the contained gases. This apparatus there-fore contains incombination one or more compressors or pumps vulnerable to corrosion butprotmted against the efleets of moist gases by regulating thetemperature of the compressors,

Ill

dbl

ing and cooling of the gases which takes place in the series of pumps24, 24", 24, and their successive coolers, progressively removesmoisture from the gases with the important result that not only isthevolume of the gas reduced, tlfus reducing the power required tohandle the gas, but the vsteam resulting from the moisture in the gas isin part taken out at each stage and therefore does not have to becompressed at a succeeding stage, thus avoiding the expenditure of powerwhich would otherwise be required to compress the steam. The drying ofthe gases which results from the repeated compressing and cooling alsoserves in a measure to protect the apparatus from the injurious effectsof the corrosive acids, which are much more pronounced when the gasesare Wet than when they are dry. Although I have shown three p mps andcoolers comprised in this multiple stage compressing and cooling systemit will be understood that this is only by way of illustration, and twoor any larger number. as desired, might be used to produce repeatedcompressing and cooling of the gases from the vacuum up to the finalcompression desired. Moreover, so far as certain of the other aspects ofthe invention are concerned a single pump and cooler might be used atthis point.

However, if only one unit or pump is used for maintaining a vacuum onthe intake side and compressing the gases on the delivery side, theCOIIIP'LGSSiOIl made bv a single unit is so extensive that it creates atemperature such that it is necessary or advisable to cool the pump toprotect it from overheating. If the pump has to be cooled it isdifiicult to control the temperature so that .it will not at some placein the pump fall below the dew point of the gases and damage the pump.But by'gradually compressing the gases in repeated stages by a pluralityof pumps, and cooling the gases to remove the water vapor between thepumps, this difiiculty is overcome because the temperature of compres-'sion at each stage is much less: and although the dew point of the gasis raised somewhat at each stage of the compression, the temperature isalso raised by the compressionfast enough to offset this effect, withthe result that the gases remain dry. Also as part of the water vapor istaken out in each of the several coolers the dew point of the gas islowered by each cooler before the gas passes to the next pump, thus byeach cooler lowering the necessary temperature for the next pump.

The gases thus cooled and dried pass out of the top of cooler 30 throughpipe 31 to a compression pump 32, by which the gases are compressed anddelivered into a condenser 33 cooled by brine or other agency, wherethey become liquefied as the combined result of ressure and lowtemperature. The liquefied gas is stored in a contamer 34.

Between the compressor 32 and the condenser 33 .is a trap 35 containingliquid sulfur dioxid, which acts as a desiccator to absorb the lasttraces of moisture from the compressed gas passing therethrough from thecompressor 32. Liquid SO can hold only small amounts of watery-but asthe water content of the gas is now very small it will be effectivelyabsorbed by the liquid SO anl it has been found in practice that onlyabout 2% of water will remain in the sulfur dioxid in the condenser 33.

The liquid $0 in trap v35 with its content of absorbed water may beblown back through the pipe 36 controlled by a valve 37 into the cooler30. It expands in cooler 30 on account of the sudden drop in pressurefrom trap 35 to cooler 30, thus refrigerating the cooler, and also givesup at least a part of the absorbed moisture which is condensed out inthe cooler.

Thus a part of the liquid SO produced by the process is used to get outsubstanever, less necessity for this than in the case of the other pumpsbecause the gases come to the compression pump 32 drier than to theother pumps, having given up most of their remaining moisture in cooler30.

I claim:

1. Apparatus for obtaining sulfur dioxid from material containing thesame, compris- I to their contained liquids.

ing a vacuum extractor,

2. Apparatus for obtaining sulfur dioxid from material containing thesame, comprising a vacuum extractor, a 'acuum pump adapted to maintain apartial vacuum in the extractor and means to control the temperature ofthe pump wherclrv the latter ma be maintained at a temperature adapterto raise the temperature of the gasesin immediate contact with the pumpabove the dew point with respect to their contained liquids. 3.Apparatus for obtaining sulfur (llOXltl.

from material contammgthe same, comprising a vacuum extractor, a vacuumpump adapted to maintain a partial vacuum in the extractor, and a jacketpump through which may be circulated a temperature controlling medium tomaintain the temperature of the pump at a point toraise the temperatureof the gases in immediate contact with the pum dew point with respect totheir contained liquids.

4. Apparatus for obtaining sulfurdioxid from material containing thesame, comprisa vacuum pump adapted to maintain a partial vacuum in theextractor, a compression pump for cornpressing the extracted gases, andmeans to heat one or both of said pumps to a temperature adapted toraise thetemperature of the gases in immediate contact therewith abovethe dewpoint with respect to their contained liquids.

5. Apparatus for obtaining sulfur dioxid from material containing thesame, comprising a vacuum extractor, means for maintaining a partialvacuum in the extractor and for compressing the extracted gases, areceiver for the compressed gases, and a trap containing liquid sulfurdioxid through which the gas passes, located in the path of the gasesbetween ,the vacuum producing means and the receiver, to absorb moisturefrom the gases.

6. Apparatus for obtaining sulfur dioxid from material containing thesame, comprising a vacuum extractor, means for maintaining a, partialvacuum in the extractor, a compression pump for compressing theextract-ed gases, a receiver to which the compression pump delivers, anda trap containing liquid sulfur dioxidthrough whichthe gas passes andthe receiver to absorb moisture from the compressed gas.

7. Apparatus for obtaining sulfur dioxid from material containing thesame, comprising a vacuum extractor, means for maintainsurrounding theabove the between the compression pumping a partial vacuum in theextractor, a compression pump for compressing the extracted gases, areceiver to which the compression pump delivers, and means between thecompression pump and the receiver adapted to liquefy and hold the bodyof sul fur dioxid, whereby moisture in the compressed gas passingincontact with said liquidsulfur dioxid will be absorbed thereby.

8. Apparatus for obtaining sulfur dioxid from n1aterialcontaining thesame, comprising a vaculuiiextractor, means for maintaining a pai' t-ialvacuum'in the extractor, a cooler toijwhich the extracted gases aredelivered from the vacuum producing means, a compression pump forcompressing the ex tracted and cooled gases received from the cooler, atrap to which the compression pump delivers containing liquid sulfurdioxid by which moisture in the compressed ,gaspassing therethrough isabsorbed, and

the compressed gas passing therethrough is absorbed, and meansconnecting the trap to the cooler to deliver said liquid sulfur dioxidinto the cooler.

10. Apparatus for obtaining sulfur dioxid from liquid containing thesame, comprising a chamber constituting a combined vacuum extractor andexhaust steam condenser,

means for delivering liquid containing sulfur dioxid into said chamber,means for maintaining a partial vacuum in said chamber, and means fordelivering the exhaust from a steam engine into said chamber, wherebythe heat of the exhaust from the steam engine will in conjunction withthe vacuum extract the sulfur dioxid gas from the liquid, and the liquidwill in turn condense the exhaust steam.

11. Apparatus for obtaining sulfur dioxid from material containing thesame, comprising a vacuum extractor, a plurality of alternately arrangedpumps and coolers, arranged in series, connected to the extractor andadapted repeatedly and pro ressively to compress and cool the gas and sodeprive it of moisture, and means to remove the condensed moisture fromthe several coolers.

12. Apparatus for obtaining sulfur dioxid from material containing thesame, comprising a vacuum extractor, a plurality of alternately arrangedpumps and coolers, ar-' ranged in series, connected to the extractor andadapted repeatedly and progressively to compress and cool the extractedgas and so deprive it of moisture, means to remove the condensedmoisture from the several coolers, a receiver for the compressed gas,and a trap containing liquid sulfur dioxid through which the gas passeslocated in the path of the gas between the pumps and the receiver toabsorb moisture from'the compressed gas. J u

13. Apparatus for obtaining sulfur d1ox 1d from material containing thesame, comprising a vacuum extractor, a vacuum pump for maintaining apartial vacuum in the extractor and compressing the extracted gases,means to control the temperature of said pump to maintain it above thedew point of the extracted gases with respect to their containedliquids, 'a cooler to which said pump delivers the gases, and one ormore additional pumps and coolers, arranged in series with said vacuumpump, the successive pumps and coolers being adapted repeatedly andprogressively to compress and cool thegases and so deprive them ofmoisture.

14. Apparatus for obtaining sulfur dioxid from-material containing thesame, comprising a vacuum extractor, a vacuum pump for maintaining apartial vacuum in the extractor and compressing the extracted gases,means to control the temperature of said pump to maintain it abovethedew point of the extracted gases with respect to their containedliquids, a cooler to which said pump delivers the gases, and one or moreadditional pumps and coolers, arranged in series with said vacuum pump,and means to control the temperature of such additional pump or pumps tomaintain the same above the dew point of the gases with respect to theircontained liquids.

Y 15.--Apparatus for obtaining sulfur dioxid from material containingthe same, comprising a-vacu-um extractor,a vacuum pump for maintainingapartial vacuum in the extractor and compressing the extracted gases,means to control the temperature of said pump to maintain it above thedew point of the extracted gases with respect to their con- 'tainedliquids, a cooler to which said pump delivers. the gases, and one ormore additional pumps and coolers, arranged in series with said vacuumpump, the successive pumps and coolers being adapted repeatedly andprogressively to compress and cool the gases and so deprive them ofmoisture, a receiver for the compressed gases, and a tra containingliquid-sulfur dioxid located in the path of the gas between the pumpsand the receiver.

16. Apparatus for obtaining sulfur dioxid from material containing thesame, comprisadapted to keep ing a vacuum extractor, a compressor andcooler connected to the extractor and adapted respectively to compressand cool the gas and so deprive it of moisture, the compressor beingmade of wear-resisting material subject to corrosion at temperaturesbelow the dew point of the contained gases, and the cooler being made ofmaterial relatively invulnerable to corrosion, and means to control thetemperature of the compressor the temperature of the gases in immediatecontact with the compressor above the dew point with respect to theircontained liquids.

17. Apparatus for obtaining sulfur diox id from material containing thesame, comprising a vacuum extractor, a plurality of alternately arrangedcompressors and coolers, ar-

- ranged in series, connected to the extractor and adapted repeatedlyand progressively to compress and cool the gas and so deprive it ofmoisture, the compressors being made of wear-resisting material subjectto corrosion at temperatures below the dew point of the contained gases,and the coolers being made of material relatively invulnerable tocorrosion, and means to control the temperature of the compressorsadapted to keep the temperature of the gases in immediate contact withthe compressors above the dew point with respect to their containedliquids.

18. Apparatus for compressing and drying sulfate dioxid gas whichcomprises a pump, a receiver to which the pump delivers, and a trapcontaining liquid sulfur dioxid through which the gas passes, locatedbetween the pump and the receiver to absorb moisture from the compressedgas.

19. Apparatus for compressing and drying sulfur dioxid gas whichcomprises a pump, a receiver to which the pump delivers, and meansbetween the pump and the receiver adapted to liquefy and hold a body ofthe sulfur dioxid gas, whereby moisture in the compressed gas passing incontact with said liquid sulfur dioxid will be absorbed thereby.

20. Apparatus for compressing and drying sulfur dioxid gas whichcomprises a cooler, means to deliver the gas to the cooler, a pump forcompressing the cooled gases received from the cooler, a trap to whichsaid pump delivers containing liquid sulfur dioxid by which moisture inthe compressed gas passing therethrough is absorbed, and meansconnecting said trap to the cooler to deliver liquid sulfur dioxid intothe cooler.

21. Apparatus for compressing and drying sulfur dioxid gas whichcomprises a plurality of alternately arranged pumps and coolers arrangedin series and adapted repeatedly and progressively to compress and coolthe gas and so deprive it of moisture, and means to remove the condensedmoisture from the several coolers.

, means to control the temperature of said pumps to maintain the sameabove the dew point of the gases with respect to their containedliquids, and means to remove the con- 'densed moisture from the severalcoolers.

23. Apparatus for compressing and dryin sulfur dioxid gas whichcomprises a plura ity of alternately arranged pumps and coolers arrangedin series and adapted repeatedly and progressively to compress and coolthe gas and so deprive it of moisture,

sulfur means to remove the condensed moisture from the several coolers,a receiver for the compressed as, and a trap containing liquid dioxithrough which the gas passes located in the path of the gas between thepumps and the receiver to absorb moisture from the compressed gas.

24. Apparatus for compressing and drying sulfur dioxid gas whichcomprises a compressor or compressors and a cooler or coolers, adaptedrespectively to compress and cool the gas and so deprive it of moisture,the compressor or compressors being made of wear-resisting materialsubject to corrosion at temperatures below the dew point of thecontained as, and the cooler or coolers being made 0% materialrelatively invulnerable to corrosion, and means to control thetemperature of the compressor or compressors adapted to keep thetemperature of the as in immediate contact therewith above t e dew pointwith respect to its contained liquids.

Signed b me at Boston, Massachusetts, this tenth ay of July, 1919.

AUGUSTUS H. EUSTIS,

